Die casting machine plunger tip



y 1962 G R. MORTON DIEv CASTING MACHINE. PLUNGER TIP Filed NOV. 17,1958- GLEN RLMORTON IN VENTORI psi 3,046,621 DIE CASTING MACHINE PLUNGERTH Glen R. Morton, 7025-5. Sarpy, Omaha, Nebr. Filed Nov. 17, 1958, Ser.No. 774,804 3 Claims. (Cl. 22-68) This invention relates to cold chamberdie casting machines and more particularly it is an object of thisinvention to provide an improved plunger tip for providing a better sealagainst the walls of the slot chamber so as to prevent flashing.

Heretofore plunger tips have worn away so swiftly that the replacementof the plunger tip is necessary each twenty-four hours of constantrunning. The replacement of the plunger tips causes expensive loss ofproduction from down time on the machine as well as the expense ofplunger replacement.

An additional disadvantage of present plunger tips has been in thattheir wearing away permits leakage of molten metal past the plunger, asis commonly called flashing, causing slower filling of the die cavityandmore porous castings. Also the build up of casting metal solidifyingaround the conventional plunger as the metal cools causes a scoring ofthe shot chamber cylinder and expensive loss of production duringdowntime for reworking of the cylinder walls.

Objects of my invention are to provide means to make a good plunger tipseal without such clearance as would cause flashing and yet Withoutundue friction against the cylinder walls through my concept of aplunger tip which maintains a constant maximum diameter.

This application is a continuation-in-part of my copending applicationSerial No. 700,850, filed December 5, 1957, and now abandoned, for DieCasting Machine Plunger Tip.

Other and further objects and advantages of the present invention willbe apparent from the following detailed description, drawings andclaims, the scope of the invention not being limited to the drawingsthemselves as the drawings are only for the purpose of illustrating away in which the principles of this invention can be applied.

Other embodiments of the invention utilizing the same or equivalentprinciples may be used and structural changes may be made as desired bythose skilled in the art without departing from the present inventionand the purview of the appended claims.

In the drawings:

FIG. 1 is a forward end view of the plunger tip and cylinder wall ofthis invention;

FIGURE 2 is a view-in-section taken along the line 22 of FIG. 1; and

FIGURE 3 is an exploded view of a forward portion of the plunger tip.

The plunger tip of this invention is adapted for use in a die castingmachine, not shown, having a shot chamber provided with a cylindricalinner wall 12. A plunger 14 is adapted to receive on its threaded end 16a plunger tip 20 of this invention, the plunger tip 20 having a mainbody portion 22 provided with a hollow center 24 for receiving coolingwater entering thereinto through the hollo w interior 26 of the plunger14, in a conventional manner.

The forward end of the plunger rod 14 is threaded at 28 and is receivedin a threaded opening 29 which connects the hollow center portion 24 ofthe main body portion 22 with a recess 32 which opens upon the rearwardside 34 of the main body portion 22.

It will be seen that the recess 32 and the opening 29, together, ineffect, form an opening extending through the rearward side of the mainbody portion 22 providing communication with the hollow interior 24.

In accordance with this invention a soft material re- 3,946,621 PatentedJuly 31, 1962 IQQ 2 taining portion 30 is disposed spaced apart from theforward end 34 of the main body portion 22.

The soft material retaining portion 30 extends almost completely fromone side to the other transversely across the forward side 34 of themain body portion 22 although the outermost edge or circumference of thesoft material retaining portion 30 is disposed inwardly of and is of alesser diameter than the outer diameter of the main body portion 22, asbest seen at 36.

Web portions 51) interconnect the soft material retaining portion 3% andthe main body portion 22. The outer surfaces of the web portions 50define segments of a cylindrical surface.

The exterior surfaces of the web portions 50 are spaced inwardly towardthe axis of the plunger tip 20 from the outer surface 36 of the rearwardend of the soft material retaining portion 3!), whereby the exterior ofthe web portions 5% define a cylindrical surface of lesser diameter thanthe surface defined by the exterior 36 of the soft material retainingportion '30.

The plunger tip further has a forward end portion 54 attached to andextending outwardly and forwardly from the forward end 60 of the softmaterial retaining portion 3%, the forward end portion 54 having athreaded cylindrical outer surface 62 on the same axis as the main bodyportion 22.

The forward end portion 54 has a forward plug aperture 66 extendingtherethrough from its forward side inwardly, the aperture 66 alsoextending through the retaining 'portion 3% and entering upon a space 70disposed between the retaining portion 30 and the forward side 34 of themain body portion 22. The forward plug aperature 66 is for receiving aforward plug later described.

The main body portion 22 has a removal plug aperture 30 disposedextending through the forward side thereof and extending inwardly to thehollow center 24, the removal plug aperture being disposed opposite theforward plug aperture 66.

It is important that the forward plug aperture 66, the removal plugaperture 80, and the opening in the rearward side of the main bodyportion 22, which is formed by the opening 29 and the recess 32, are alldisposed in alignment whereby a tool can be inserted through the recess32 and the opening 29 and driven against the rearward side of a removalplug disposed in a removal plug aperture 80 driving the removal plug 90against a forward plug 92 which fills the forward plug aperture 66 fordriving the forward plug 92 out of the plunger tip to make pos sible theremoval, replacement and also filling of the space 7d with the mass ofmaterial which is later described.

A plurality of rings are disposed forwardly of the forward side 34 ofthe main body portion 22 and are arranged with their exterior'surfacesin a cylindrical configuration substantially of the same diameter of themain body portion 22, the rings 110* each actually being a ring segmentor a substantially complete circular ring with the exception of acut-through portion 112 at at least one place in each ring to permitexpansion of the outer diameter of the ring for completing filling andsealing the inner wall 12 of the shot chamber and as the exteriorsurfaces of the ring 110 wear away and as later described.

The inner diameter of the rings 110 are such that they are adapted to bereceived between the exterior surface 36 of the soft material retainingportion 30 and the exterior cylindrical surface of the plunger tip.

The mass of soft material 100 must be of a material adapted to changeshape under normal pressures and temperatures of the shot chamber of acold chamber die casting machine whereby the outer surfaces of the ring11% gradually wear away, the pressure in the shot chamber will cause theforward plug 92 to be driven inwardly and reaiwardly of the tip, forcingthe mass of material 100 to change its shape and to move outwardly forhaving a larger outer diameter, thereby exerting pressure against therings 110 causing them to be forced outwardly against the shot chamberwalls 12 for providing a snug fit to eliminate flashing.

I have found a soft aluminum alloy which is of substantially purealuminum to be an excellentmaterial for the mass 100 and also zinc willwork, although less effectively.

I have found that the rings 110 work best if formed of beryllium copperas this material tends topolish the cylinderwall 12. However othermaterials will also work.

As thus described, it will be seen that this invention provides aplunger tip which maintains, through the movement of the rings 110outwardly, a substantially constant diameter regardlesstof wear on theouter surfaces of the rings 110.

Asaresult the problems of flashing are eliminated along with the greatlabor costs of plunger tip replacement, cylinder wallresurfacing; andalso the loss of production through down-time is greatly reduced. Theporosity of the castings also increases because of the possibility ofmaintaining a constant pressure on the molten metal in the die cavitythrough elimination of flashing.

Arring retaining nut 114 threadedly received on the for- Ward endportion 54 of the plunger tip 20 in final assembly, as shown in FIGURE2, secures the rings 110 in position.

From the foregoing description, it is thought to be obvious that diecasting machine plunger tip constructed in, accordance with my inventionis particularly well adapted for use, by reason of the convenience andfacility with which it may be assembled and operated, and it will alsobe obvious that my invention is susceptible of some change andmodification without departing from the principlesand spirit thereof,and for this reason Ido not wish to be understood as limiting myself tothe precise arrangement and formation of the several parts herein shownin carrying out my invention in practice, except as claimed.

I claim:

1. A plunger tip for a die casting machine comprising: a main bodyportion of cylindrical shape having a hollow center having an openingextending through its rearward side,sa soft material retaining portionspaced apart from the forward end of said main body portion providing anannular space between the material retaining portion and said main bodyportion, web portions interconnecting said soft material retainingportion and said main body portion, the exterior of said web portionsbeing spaced in- 'wardly toward the axis of the plunger tip from theexterior of: the rearward end of said soft material retaining portion, aforward end portion attached to and extending outwardlyv from theforward end of said soft material retaining portion and having athreaded cylindrical outer surface having the same axis as said mainbody portion,

said forward end portion having a forward plug aperture extendingthrough said forward end portion from the forward side inwardly and alsothrough said retaining portion, a forward plug in said forward plugaperture, said main body portion having a removal plug aperture disposedextending through the forward side of said main body portion inwardly toits hollow center opposite said forward plug aperture, said forward plugaperture and said removal plug aperture and said rearward side openingof said main body portion all being disposed in alignment, a pluralityof ring segments disposed forwardly of said main body portion andarranged with their exterior surfaces in a cylindrical configurationapproximately of the same diameter as said main body portion, and amassof soft solid material adapted to change shape under the pressures andtemperatures of die casting machine shot chambers, said mass beingdisposed in and filling the space between said material retainingportion and saidmain body portion whereby as the exterior of said ringswears away said forward plug moves rearwardly under the pressure in saidshot chamber causing said mass of material to change shape and exertpressure against said rings to hold them outward to provide them with asubstantially constant outer diameter.

2. A plunger tip for a die casting machine comprising: a main bodyportion of cylindrical shape having a hollow center having an openingextending through its rearward side, a soft material retaining portionspaced apart from the forward end of said main body portion, said bodypor tion and spaced material retaining portion defining a spacetherebetween web portions interconnecting said soft ma terial retainingportion and said main body portion, the exterior of said web portionsbeing spaced inwardly toward the axis of the plunger tip from theexterior of the rearward end of said soft material retaining portion, aforward end portion attached to and extending outwardly from the forwardend of said soft material retaining portion, said forward end portionhaving a plug aperture therethrough opening at the forward end thereofand extending inwardly to and through the space between said retainingportion and said main body portion, a plug slidably received in andsealing said plug aperture, a plurality of ring segments disposedforwardly of said main body portion and arranged with their exteriorsurfaces in a cylindrical configuration approximately of the samediameter as said main body portion, means attached to and disposedforwardly of said soft material retaining portion and extendingoutwardly alongside said rings for preventing said rings from movingforwardly off of said plunger tip, and a mass of soft solid materialadapted to change shape under the pressures and temperatures of diecasting machine shot chambers, said mass being disposed in andfillingthe space between said material retaining portion and said mainbody portion whereby as the exterior of said rings Wear away said plugmoves rearwardly under the pressure in said shot chamber causing saidmass of material to change shape and exert pressure against said ringsto hold them outward to provide them with a substantially constant outerdiameter.

3. A plunger tip for a die casting machine comprising: a main bodyportion of cylindrical shape having a hollow center having an openingextending through its rearward side, a soft material retaining portionspaced apart from the forward end of said main body portion and having acylindrical outer surface of lesser diameter than said mainbody portion,said body portion and spaced material retaining portion defining a spacetherebetween, webportions interconnecting said soft material retainingportion and said main body portion, the exterior of said web portionsbeing spaced inwardly toward the axis of the plunger tip from theexterior of the rearward end of said soft material retaining portion, aforward end portion attached to and extending outwardly from the forwardend of said soft material retaining portion and having a threadedcylindrical outer surface having the same axis as said main bodyportion, said forward end portion having a forward plug apertureextending through said forward end portion from the forward sideinwardly and also through said retaining portion, said main body portionhaving a removal plug aperture disposed extending through the forwardside of said main body portion inwardly to its hollow center oppositesaid forward plug aperture, said forward plug aperture and said removalplug aperture and said rearward side opening of said main body portionall being disposed in alignment, a forward plug in said forward plugaperture, a removal plug in said removal plug aperture, means forpreventing said removal plug from moving forwardly out of said removalplug aperture, a plurality of ring segments disposed forwardly of saidmain body portion and arranged with their exterior surfaces inacylindrical configuration approximately of the same diameter as saidmain body portion, and a mass of soft solid material adapted to changeshape under the pressures and temperatures of die casting machine shotReferences Cited in the file of this patent UNITED STATES PATENTS MurrayMar. 17, 1925 Lannert Mar. 8, 1938 Sauzedde Oct. 25, 1938 Bennett Oct.18, 1949

